The prior art discloses printed electronic circuits in the case of which circuit boards are populated with electronic components. Such circuit boards may consist of one or more individual layers of fibreglass-reinforced, cured epoxy resin sheets that are copper-clad on one or both sides for the formation of traces. This arrangement of one or more individual layers is referred to in the present case as the “circuit board body”.
Because of the relatively high loss of power of the electronic components arranged on it, a circuit board that has been populated with components and is in operation undergoes the development of a great amount of heat. To dissipate the heat that is attributable to the loss of power, it is known to provide a heat conducting element in the form of a metal body. The heat conducting element often consists of copper or a comparable material that has good heat conductivity. The heat conducting element provided in the circuit board ensures sufficient removal of the lost heat from the electronic components and thereby prevents the components and the circuit board from reaching a critical temperature range.
Apart from the heat conduction, the heat conducting element often has the additional function of providing an earth connection for the component concerned. In the case of a known arrangement, the electronic component is in thermal and electrical contact with the heat conducting element through a clearance in the circuit board body. The fact that the heat conducting element provides a low-resistance electrical connection to an earth layer of the circuit board is then of particular importance. In the case of high-frequency arrangements, there is additionally the requirement to provide the earth contact between the heat conducting element and the earth layer of the circuit board as close as possible to the electronic component, so that the buildup of interference fields is suppressed. The above earth layer of the circuit board usually extends over a significant part of the surface area of the circuit board body.
In the case of the circuit board in question, the heat conducting element is connected to a surface of the circuit board body by way of an adhesive boundary layer. This involves using an electrically and thermally conducting adhesive, which provides the electrical contact between the heat conducting element and the earth layer of the circuit board. The conducting boundary layer in this case extends over a large surface area of the heat conducting element.
The fact that it is costly to use the conductive adhesive over a large surface area is problematic in the case of the known circuit board.
The invention addresses the problem of configuring and developing the known circuit board in such a way that less costly production is possible.